Nonunion of the scaphoid: a critical analysis of recent natural history studies.

To determine whether treatment of a disorder is effective, a surgeon must first understand the natural history of the disorder without treatment. We used guidelines for the performance of a valid natural history study that appear in the literature and applied them to articles on the natural history of scaphoid nonunion. No study satisfied all criteria. Moreover, none developed an inception cohort, which is the single most important method of a valid natural history study. In each study, the direction of the bias was identifiable: the natural history of scaphoid nonunion was distorted to make the outcome more severe than if methodologic problems had not been present. We conclude that the natural history of nonunion of the scaphoid is not as severe as has been reported in the literature. The magnitude of the difference is not known at this time.